Error CS0234: The type or namespace name 'AspNetCore' does not exist in the namespace 'Microsoft' (are you missing an assembly reference?)

Question

I'm trying to upgrade the following template project to ASP.NET Core 1.1: https://github.com/wilanbigay/aspnet-core-aurelia-typescript-starter

After running dotnet migrate the project.json file has been dropped in favour of the new csproj file.

Using Visual Studio Code and the Nuget4Code extension I've upgraded all components to ASP.NET Core 1.1.

The CsProj now contains entries like so:

<ItemGroup>     <PackageReference Include="Microsoft.NET.Sdk">       <Version>1.0.0-alpha-20161104-2</Version>       <PrivateAssets>All</PrivateAssets>     </PackageReference>     <PackageReference Include="Microsoft.NET.Sdk.Web">       <Version>1.0.0-alpha-20161104-2</Version>       <PrivateAssets>All</PrivateAssets>     </PackageReference>     <PackageReference Include="Microsoft.NETCore.App">       <Version>1.1.0</Version>     </PackageReference>     <PackageReference Include="Microsoft.AspNetCore.Mvc">       <Version>1.1.0</Version>     </PackageReference> 

However I have compilation issues. It seems the AspNetCore namespace can't be found. I'm getting the error

Error CS0234: The type or namespace name 'AspNetCore' does not exist in the names pace 'Microsoft' (are you missing an assembly reference?)

I'm not sure how I can check references like I used to be able to in Visual Studio in the references section. How can I resolve this?

Answer 1

We just had this issue where visual studio helpfully added a local reference rather than going via nuget

<ItemGroup>   <Reference Include="Microsoft.AspNetCore.Mvc.Core">     <HintPath>C:\Program Files\dotnet\sdk\NuGetFallbackFolder\microsoft.aspnetcore.mvc.core\2.0.0\lib\netstandard2.0\Microsoft.AspNetCore.Mvc.Core.dll</HintPath>   </Reference> </ItemGroup> 

Removing this and referencing via nuget solved the problem, looks like an issue in Visual Studio 2017.

Answer 2

So I guess I was referencing the dependencies but didn't have them installed for the project.

All I needed to do was run dotnet restore

https://docs.microsoft.com/en-us/dotnet/articles/core/tools/dotnet-restore

As stated in the link above this "Restores the dependencies and tools of a project."